1. Technical Field
Aspects of the present invention relate to a rubber key device having a key top portion formed with an operation face, which is provided with a plurality of depression areas along its periphery, a rubber key being arranged on an opposite side of each depression area. When each depression area is depressed, the rubber key corresponding to the depression area is depressed. Aspects of the invention also relate to a portable terminal device and image processing device employing such a rubber key device.
2. Related Art
Conventionally, the rubber key device as described above is employed in various electronic devices such as a facsimile apparatus and a telephone. In such an electronic device, the rubber key is used as a multi-selection key used for selecting one of multiple candidate items. An example of such a device is disclosed in Japanese Patent Provisional Publication No. P2001-250455A (hereinafter, referred to as '455 publication).
As a concrete example of a device employing the rubber key device, a cordless handset of a facsimile apparatus or a telephone will be described with reference to FIG. 10, which schematically shows a configuration of the cordless handset 100 which is used in association with a main device (not shown).
As shown in FIG. 10, the cordless handset 100 is provided with an operation panel 108 which is provided with multiple keys such as numerical keys for inputting numerals and letters/symbols, four-direction key 106 for selecting one of multiple functions or items, a display 110 for displaying operation status of the operation panel 108, a communication status with an opponent when an audio communication is being performed, an earpiece 112 configured to output an audio message via a built-in speaker and a mouth piece 114 through which voice of the user is transmitted to a built-in microphone.
Surfaces (operation faces) of the multiple keys and four-direction key 106 provided to the operation panel 108 are respectively exposed to outside through openings that are formed at predetermined positions on a case 102. For example, for the four-direction key 106, a cross-shaped opening 104 is formed on the case 102, and the top surface (i.e., an operation surface) of the four-direction key 106 is exposed to outside through the opening 104.
As shown in FIG. 10, the four-direction key 106 is configured to have four depression areas (up, down, right and left in FIG. 10) along its peripheral, and the four depression areas are assigned with different functions or selective items, respectively. When one of the depression areas is depressed by a user, a function or a selective item assigned to the depressed area is selected.
Now, a rubber key device including a plurality of rubber keys for the four-direction key 106 of the cordless handset 100 will be described in detail, referring to FIGS. 11A and 11B. FIGS. 11A and 11B each shows a cross-sectional side view, taken along line A-A in FIG. 10, of the rubber key device employed in the cordless handset 100.
The cordless handset 100 is provided with a rubber key sheet 120. The rubber key sheet 120 is provided on a printed circuit board 116, and has rubber keys 123, 123, 123 and 123 corresponding to the up, down, right and left depression areas of the four-direction key 106. Among the four rubber keys 123, 133, etc., one corresponding to the up depression area of the four-direction key 106 has a cylindrical shape which is circular when viewed from the four-direction key 106 side. On a lower side (i.e., the printed circuit board 116 side) of the cylindrical rubber key, over an peripheral end thereof, a skirt portion 125 is formed, which is connected to a base portion 121. The rubber key 133 corresponding to the lower depression area of the four-direction key 106 in FIG. 10 has the similar structure, and is connected to the base portion 121 via the skirt portion 135 (see FIG. 11A). Although not shown, the rubber keys corresponding to the right and left depression areas of the four-direction key 106 have the same structure. The rubber keys 123, 133, etc., the skirt portions 125, 135, etc., and the base portion 121 are formed integrally using the same rubber member, and form the single rubber key sheet 120 as a whole.
The skirt portions 125 and 135 are intended to generate a so-called “click feel” when the corresponding rubber keys 123 and 133 are depressed. That is, the rubber keys 123 and 133 are elastically supported by the skirt portions 125 and 135, respectively, with respect to the base portion 121. If the rubber key 123 corresponding to the up depression area of the four depression areas is depressed toward the printed circuit board 116 side, the skirt portion 125 elastically deforms and the rubber key 123 moves toward the printed circuit board 116. The deformation of the skirt portion 125 generates the “click feel”. With this configuration, when the user depresses the rubber key 123 (133) directly or indirectly, he/she feels the “click feel” generated by the deformation of the skirt portion 125 (135) and recognizes the key is fully depressed.
As above, if the user depresses the upper depression area of the four-direction key 106, as shown in FIG. 11B, the four-direction key 106 rotates counterclockwise (in direction Q in FIG. 11B) about a point P which is a point at which an end of the four-direction key 106 at a position opposite to the depressed area and the case 102 contact. Then, by a bottom surface 107 of the four-direction key 106, the upper surface of the rubber key 123 is depressed. Then, a movable contact 127 formed on a bottom surface of the rubber key 123 electrically contacts a fixed contact 129 formed on the printed circuit board 116.